EC300 losing power + rattle
 

Ok so I've had this problem appear 2 rides ago, I'm forming a theory but won't get to check it for a while. On that ride I was putting the bike under load going up a hill, but certainly had done bigger hills that this, not intense, in fact earlier I had done a long steep uphill with no drama.

Anyways the bike starts making a rattle & loosing power to the point I decide to stop & restart. I nurse the bike back to the pits & decide what to do. But it is now running fine. I start off for another loop & thrash it just in case if shows an error I can shortcut out of the loop. Runs fantastic, pulls good wheelies. Then stutters coming out of a shallow river crossing.

So back home pull it down & PV is smoothly turning, piston is peachy but very worn, figured that anyway, but no pick ups, no deto marks. Crank seems fine with no movement I can detect wobbling the crank ends or the rod, no discolouring. As you?d expect an 07 to be really.

New piston, fire it back together, adjust the PV so there is no slop (not really much before) in the governor arm.

Next ride yesterday.
All went well, less rattle, ran it in, all good, bike peters out on a hill again with accompanying rattle. No power almost to a stop. Give it a few seconds still running & it comes right & returns to full power. Do rest of 25k loop with no problem.

By now I'm thinking carb float sticking. But makes a rattle that doesn't make me think its running out of gas, but maybe that is deto from lean mixture on a big cylinder under load.

Don't fancy taking carb apart in a field so do a loop on the Trials bike I brought along (its ok it's a GG). Go out & do another loop on the EC300. Up a hill & it looses power again & actually stop, then blipping it trying to keep it running & it stops. Then 10 sec restart it & it clears out & runs fine. Although a few times under load I notice a tendency to seem like it is teetering on the edge. I also notice a few knocks like deto.

So clearly I will pull the carb & check the float valve & check float height. But seems queer as the carb hasn't been apart for several rides. No mechanical issues I can see, even the reeds looked nice from the crank case (top end removed) with a torch.

Water would stop it & make it backfire I would have thought.

Any other ideas?


OK further thoughts. The pipe is a euro road catalytic pipe that was cut open & the cat removed. For some strange reason it rattles more than the other pipe (which is a bit squished). Small poss that something is dislodged & blocking the pipe somewhere. Had this pipe on for about 3-4 rides before seeing an issue.

Can't see the ign going into some queer mode, but possible I guess (happens on rain & full power mode).

So open to the panel:

Ideas :) ..I'm an ideas man!!

I noticed when my powervalve stuck open the engine sounded rattley like it was about to blow up. The bike was so soft on power that it could hardly pull me around off the pipe, and the engine sounded so ill that I didn't dare rev it hard enough to put it on the pipe. Limped it home.

When you checked the powervalve actuation was it with the cylinder off? Did you rotate the powervalve through a frull 360 degrees forward and back? I found mine would sometimes hook up on the return. Other times not. A good clean of the entire assembly fixed it up.

Also an easy check if you think its running lean on you, cut the engine when it plays up under load and pull the plug. It'll tell you how its feeling. You could possibly use this to check the location of the PV as well if you popped the LHS off, or pipe/RHS (both). Depends where you are when it happens next.

If you suspect water in the fuel it will be evident in the carb drain bolt as the lowest part of the system.

Hmmm
 

Have had a similar issue with my 2010 300. I have had a couple occurrences where I get a rattle/change in pitch and slight decrease in power, maybe. 10% decrease. This lasts for a few seconds and goes away. It seems to happen when i hit a large rock or root-some on here associated this with the pipe taking a hit and loosing its seal with the head.

Hmmm

I'm talking about an 80% change in power. As I said it actually stopped at one point, it was very dead feeling trying to blip it.

I had the barrel off when I changed the piston & I decided not to pull the PV as it seemed so smooth through operation. The governor seemed to move ok but can only push a little due to spring. Its bathed in oil so shouldn't be a problem, but can't rule that out, I started to take it apart to check the balls & didn't go any further when it seemed ok.

Interesting that you (Jakobi) had similar symptoms, but maybe not quite. I'll keep it in mind for sure.

I don't think the plug would change that quickly, remember that it runs great most of the time & then Nunnnggg rattle rattle.

Only takes a few secs to change a plug up, especially if its extreme enough to cut the engine out :cool:

My symptoms never came and went though. When mine stuck it stock wide open until I removed the RHS power valve. When I went to crack the lock nut on the actuator arm the valve returned to normal. I unclipped the arm and ran the valve between its stops. Fine smooth action hooked it up and it stuck at wide open again. It wasn't until I removed the stops and ran the actuator plate through its full motion in forward and reverse that I noticed some minor binding on reverse. It wouldn't happen at the same time or the place. Ended up being some carbon deposits.

I would say that I would have lost 80% power easily. Scared the shit out of me as I'd just been making jetting changes before it happened. It honestly felt and sounded like the rings had fallen off the piston. Would not idle well either.

so what ditd you do to repair it, just clean?

http://www.gasgasons.com/index.php?s...c&staticID=133

Above shows step by step with pics. Pulled the assembly. Cleaned the carbon off everything. Repacked the bearings with grease after checking they were running smooth. Re assembled. No issues since.

Power loss, rattle, knock equals lean to me. The fact that it happens on hills and after a water crossing is suspect. How are your carb vent lines routed? Are they clear? All down is bad. Split them and route the pair from the vertical fittings up high as has been discussed here many times. Also check/clean carb as it can suck dirty water if all lines are routed down.

Don't overlook the gas cap, cost me a race once. The pin holes in the rubber insert/gasket can swell shut and block venting. Cut this middle section out(or replace it with a homemade ring gasket), enlarge the holes in the plastic retainer for the check ball, glue this back on and make sure the ball is free.

Try the simple things first, PVs and pistons don't care about hills.


Jakobi,

The PV bearings are best just cleaned well or replaced (cheap) and lubed with a little two stroke oil. Spooge oil keeps them alive in use. If you run a good high flash point oil they should never be fouled with hard deposits.

Thanks for the info Glenn,

I had given the bearings a good clean first and considered replacing but there was no play or binding in the bearing itself. Mine was some carbon on one of the powervalve rollers (either side of the main flap). I had been using GGs recommended GRO at 50:1 as per requiresments of GG aus in order to retain my warranty. Since that is now up I am trying Amsoil Dominator. Have only ran half a tank through it so hard to comment yet.

Good thinking re the gas cap/vents. I don't know how many times something simple like this has stopped a bike from running.

Does the engine get a lean surge like its running out of gas before it dies?

Thanks guys I'm getting some good alternative info here, hadn't thought about the gas cap & yet have had this problem on roadrace bikes.

Carb vents. . . erm, heck you know I can't remember. I definitely went through the 200 & did them up & out of the way/airbox. Can't remember if I did the 300 fully.

Re the engine lean surge, well, it would be masked, if you are going up a hill you are under load so you won't get a surge, just a big loss of power then the gas would get so low that it would hardly run. That is what made me think carb, but tank venting is an interesting alternative & why these forums are a good sounding board.

Have you looked at your stator?

yes, its kind of round & metally. & underneath I noticed there were a bunch of wires tightly wound round some formers.

ROFL at the stator comment :D Very descriptive!

Even though the bike will run low on power my first impulse would be to pull the clutch and stop if it was dying out that bad. I'm sure you'd get the tell tale up and down lean surge prior to it dying. I could be wrong. I also think if its under enough load to die without surging that the spark plug should give you a pretty good reading of it being lean.

Well I wasn't quite sure what he was getting at & if find, being a sarcastic twat is usually the best answer. However on occasion you miss a reasoned reply, but with one liners its a bit miss more than hit.

Yeah it pretty much was always on a hill, but not every hill, in fact there were quite a few in 25-30k loops. If it was occurring on the flat you would get the btchy lean stammers, but I think under load with a big cylinder maybe as the gas runs low in the float bowl it just loses a heap of power & detonates from being lean, -Heck I dunno, that's why I'm asking, I'm used to smaller capacity roadrace bikes.

by the time you pull the clutch & bearing in mind this happens within 20M at a speed of 2nd or 3rd gear I can't see it colouring the plug.

On roadrace bikes you don't get a reading to trust until you are flat out for several seconds then pull the clutch & coast pulling the plug straight away.

Actually not much choice other than do just that, bike stammers & you go from 20kph to 2kph in no time & you whip the clutch & front brake to stop rolling back.


I'm getting some good ideas here guys, remember there are no stupid questions, only stupid people asking them.

No wait, hold on, there was a verse there I've got wrong. Work smarter not harder, two bushes in a bird & teach them to fish. Summit like that.

Let us know how you get on! I'm all out of ideas for the moment :D

Will do. Racing on tarmac this weekend but should get some time during the week to look at the dirtbike & there is a ride at the end of the month. I have a few things to check more than just the carb now.

well I blew up my race engine so last thing I needed was another bike to fix.

anyhoos I decided to quickly have a looksee at the GG to see if anything was obvious. The cap vent seemed to work, but one could see how it could clog, so I bored 3 more holes in the rubber & one more in the under-cap that retains the stop ball + some trenches so it should be hard to deform & close off airflow.

I then ran the tap into a bucket & it emptied 1/4 tank with no drama. I blocked the gas cap vent & saw it stave off flow & eventually to a trickle. So that isn't surprising.

Vents? well like a good lad I had the top ones into the airbox. Bottom ones weren't split so I cut them, but neither were they blocked.

No water in bowl, well tiny 3mm globule of ooze, but can't see you'd be so unlucky that would be a problem.

Float jet looked fine & took it out to see no restriction or with hose to tank.

Hmm, float height. Read 16mm somewhere, & must research from where to where on Keihins. From gasket face to top of float was also about 16mm. but that is with weight on spring. Hmm, what's this? one float is 2mm out from the other? Well ok I'll straighten that, but not a smoking gun.

Just done a search so will recheck. have to make a 16mm template, my vern isn't wide enough. I'll straighten the float first.

ok well that was interesting. Definitely a low float height. The needle tag of the float was bent in a queer way so it was sitting at 16mm ('07 PWK) when weight against the spring rather than tilted with spring uncompressed, so either the old owner had the dribbly carb issue or had read the instructions wrong.

I hate that measurement with tilted carb, seems so imprecise, remember it now from my 200.

So I also checked as suggested on that auss website with the carb with no float bowl & gas connected, now shuts off with float seams just before parallel, before it would have been ages before,

Smoking gun? Well well smelly one for sure.

But what is queer is that I haven't had the carb apart since changing the jetting after the first ride & rode it say 8 times since then, but I've only had this issue in last two rides. And I've done some ugly long uphills.

So I'm still a bit concerned. Should find out this weekend unless it rains too much to ride.

Thanks for ideas so far. I also fitted a R/A fuel filter. Had it for months bought on a whim looking for an application & then read people use them on the GG & it found a home.

Well - complete cure? erm no.

I was supposed to ride last week but there was some unseasonable weather in what is usually our calmest month. I rode yesterday and. . . it was better.

it didn't konk out.

However it did occasionally feel like it was losing power. Sometimes it would rip & sometimes it was soggy, certainly not the lift-wheel-on-command power it usually has. I got to a section that was a little more open & both times I passed this section I held it wide open & the bike refused to rev. Like it was running low on gas.

The plug came out after the first loop (42km) black as soot. I changed plug & the next loop it was dark but not black as before.

I was getting 9-10km/l so it was not chewing through gas or anything.

So the other part of the equation is the pipe. We de-catted it. But for some reason it still makes a vibration noise. I might try my old bashed up pipe & see if the issue goes away. there might be something else in there that somehow closes up the pipe. And then reopens to full power.

Its a long straw idea.

the other one is to swap my mates carb on there, but that is some hassle to go get it & pull it off, try it & then swap it all back again,

Got me stumped too.

I very much doubt something in the pipe is restricting and only at certain times. Ignition related perhaps?

I know we both had a chuckle about the post up the top of the page but have you removed the stator cover and had a look to see if any water has been making its way in there? Is it possible that something like that is playing havoc? Maybe its a little loose and is advancing/retarding with vibration just enough to play havoc with the power delivery and fuelling?

If you have someone you can do some part swaps with it'll at least help you to start eliminating more things.

Yeah it isn't giving up easily. I would have to say that the more I learn the more I come up against tricky problems that stretch me. i've been tuning race bikes at the pointy end for 20+ years, but still something will get me stumped for a while.

The carb seemed easy & obvious. It could still be the float height is too low, but I doubt that, I have checked. It could be the float needle is sticking or the floats snagging, but they both look just fine. Carb swap would confirm that, but it is a major hassle when you think of what is involved & getting the carb off & back on my mates bike without compromising his riding.

Stator area looked dry when I had all that off doing the repiston. Vibration would tend to move a plate one direction, I've been there. But all looked in order. Stator issues just tend to go ok when cold & part & fail when hot.

yes it could be a fault in the ign box, but it would be a weird one.

The rattle in the pipe is a mystery. What is rattling. the change over of that pipe probably coincides with the appearance of the problem, or close enough. Enough to make me suspicious.

I have two race meets coming up so I won't ride the GG till end of month earliest. I might strip the carb & look again with an eye to changing the float needle, but it looked premo.

Exhaust mounts? Worn O-rings? Powervalve? They all rattle occassionally.

Nice tight springs on the pipe, fresh Viton o-rings and extra high temp silicone work well to keep it quite for the longest. PV is generally only a clack here and there at low rpm.

I have no doubt you'll work it out sooner or later and it'll probably be something so simple we'll all wonder how it stumped us so long. Good luck

thanks mate.

Yeah spigot seals aren't that old but I'll fire new ones on. either way it seemed that one pipe makes the noise & the old beaten up original doesn't, same springs etc etc.

If I shake the pipe it makes no noise. I poked a clutch cable (remember those) up there & well there is a bit of an odd step at the middle of the baffle cone. But there is also one on the original pipe, seemingly less. Wish I could put on some x-ray specs.


Hmm, ok here's a difference. The old pipe is a stretch to get the rubber mounts aligned so they are stretched. The new pipe is a perfect fit. But resting weight against the pipe doesn't stop the rattle. it is quite noticeable, my other GG riding buddy noticed it straight off.

Just to add to my woes the g.box oil went totally milky again. Changed the impeller seal like 3 rides ago.

And the woes come in 3's.. Whats next? If it is vibing against the header it could be just a small difference in alignment. It could be something internal I guess.

The water in the oil scenario sux :( This bike sounds like my missus. Forever needing love and attention.. She makes weird noises and acts unpredicatably while riding too.. Hahah!

OK so I rode again yesterday. I'd changed the impeller seal again & preloaded it with a couple of suspension shims which apparently is an LTR trick. I changed the rad cap to a KTM one as a precaution.

I flushed the g.box with diesel a couple of times & started the bike ont he stand to splash it around in gear for a few mins. Drained milky & then not so bad. Put some cheap g.box oil in & will drain after another ride once I'm happy it is fine.

First loop & I had lost a little water, but I hadn't run it so maybe there was a pocket, filled it from my backpack, didn't take that much. Checked again a couple of times & no water loss. Gearbox oil looks sweet.


Fitted the old original but slightly dented squashed pipe. Adjusted the carb so it leaks a bit on the sidestand so there can be no question of being too low.

Bike displayed no sign of konking out. There were some long steep uphills so it was a reasonable test. However there was no long open sections so I'm still not chalking up 100% result yet.

The bike did bog a little which I put down to flooding over bumps. I lowered the float closing height (you can measure the bend of the tang quite easily & we're talking another 0.5mm, so I'm being over cautious).

Bike ran better.

I want to try a more open ride & then put the other de-cat'd pipe back on & see if the problem re emerges.

Rattle from pipe gone. Still knocks oncee when throttle closes, guess that is PV, but my 200 never did it. Hmm, clutch didn't seem to have any play in it, maybe a drive lash thing Maybe I should try a higher octane gas just to see if not deto.

I do love this bike though.

So, you are running on 91? I find 96/98 much better. "knocks once when throttle closes" sounds like you are running just a fraction lean at wide throttle settings - raising the needle just one notch may well get rid of that (but may cause other issues lower down etc.) Mine will ping like that when I'm hard out on the pipe and close/open/close the throttle.

I run it on 96, just thought I might splash in some Av to remove the possibility that the PV closes quickly being centrifugally operated raising the effective off the pipe compression quickly. maybe, easy experiment if I remember.

It does it from low throttle applications to sudden shut.

I had thought it was a tickle lean at low throttle applications when my float height was low. Now it is too rich & still does it.

Not as bad now I replaced the piston.

Ahh bugger I forgot to try some Av gas in the tank. Bike ran with none of the stalling issues, but I still have the old pipe on. I intended to try the de cat'd one but thought I'd try lose the close throttle knock, so I raised the needle a clip. Well even with as much adjustment with the air screw it ran like a complete dog.

I might have to recind my thoughts on what I thought was a well jetted bike. It didn't want to pull through & would only run well if zinged back & forth in higher revs. Never had a bike change so much with one clip. So after that loop I went the other direction & it was mint. But knock back, but seemingly not as bad, which doesn't make much sense. I might start some other needles, 'cause clearly it is borderline somewhere in the range, perhaps the new piston & maybe the other pipe just pushes it too far.

G.box oil seems clean which is nice. Must reposition the PV outlet as it got spots on my trou. I had routed it up by the rad so it didn't get flooded, but now it spits oil at me.

Do you mean knock back as in pipe bang? Like a loud 'tang' noise? I found that being rich in the lower rpm has caused this on mine in the past. Like the fuel load is building up to a point where it ignites in the pipe. I found it most prominent when running a lean clip position and a burbly rich straight diameter and pilot.

The N1Ex and NOZx needles both have a really short straight section which then starts with a very rich first taper. I found the pilot circuit and needle diameter only has a very limited effect as before you know it you're on the first taper. Its richness on the taper that also causes the huge jumps in clip position. Myself and others have found that even lifting to the very top clip isn't enough to overcome the first taper. It makes it more ridable, but still far from clean or smooth off the bottom (more punchy), and for me the biggest killing was the lack of fuel economy.

More like a Knang than a Tang, but that could be a local dialect thing:D.

Interesting, the Taper isn't supposed to affect things until after 1/4 throttle. . . unless it starts too early. From memory I have DEK, CEL (might be in my RZ) & BGNs in the jetbox, so I'll have to read up on what to try or order something different.

Thanks for the thoughts. I tells you, small capacity race bikes are so much easier to jet. WOF is all important & who cares what happens under 8000.

Could be.. :p

The point at which the first taper starts depends on clip position and the particular needle.

For example, I just measured the NOZJ that I have here by the desk. Its a half clip leaner than N1EJ. Not counting the clip section. Just the effective part of the needle the full length is 50mm. The straight section is only 5mm before the taper starts. Now consider that you will have the slide lifted a little bit to allow for an idle, you only have a few mm of straight section to use before you're onto the taper. All in all for this needle the straight section is only 10% of the equation. By lifting the clip you lengthen it which is why it helps somewhat, but as always you then hit that rich first taper.

I have an 09 ec 250 that had the exact same problem last weekend. When I was fueling the bike, I noticed the gas cap insert shrunk over the winter. I tried to stretch it out to make a good seal to the top of the tank and went riding. When the bike started acting up, I took that insert out and disconnected the vent line from the frame. Bike ran great the rest of the day.

Well just as an update I thought I'd report.

Nothing much to report. Ran the bike a few times (not much riding in winter here), but with a combination of a few things & a CCL needle it seemed to run well. Had a ride in the weekend at reasonable altitude & cold day it seemed a little lean off closed so a 1/2 turn & seemed fine. Were a few uphills & under load sections.

Put my other non dented gutted pipe on & couldn't tell the difference. No problems so far. Although there wasn't much in the way of long up hills on this loop.

No smoking gun, but as long as it runs right I'll put it down to a combination of factors. Possibly the chromed pipe increased pipe temp a bit & required slightly richer jetting so went from borderline to over lean in some area.

Must do my planned head mod to reduce squish right down but retain compression as std (so I can kick it over easily). Its in the queue.